Tropical Storm Helene formed over the northwestern Caribbean on Tuesday and triggered a tropical storm warning for the Lower Florida Keys. The storm is forecast to be a major hurricane for the Florida panhandle Thursday.

Tropical Storm Helene was rapidly strengthening in the Caribbean Sea and expected to become a hurricane Wednesday while moving north along Mexico's coast toward the U.S., prompting residents to evacuate,

Tropical Storm Helene formed Tuesday in the Caribbean Sea and could strengthen into a major hurricane while moving north toward the U.S., forecasters said.